Wireless Bridge II dropouts

We have 8 Wireless bridges are losing connection to each other. The LEDs on the units indicate otherwise - and show that a link is present. One is configured as an access point - and the other as a client. The bridges are configured as an acces point and client, each set on their own 5G channel. RSSI is good. Initially we where running on older firmware and upgraded this last week to the latest. The units do now recover from this, as previously they required a power cycle. Any logs or AT commands we can use to see what is going on?
The area has no other wifi as we are underground. Power supply is stable and UPS backed. Firmware 2.05.02